Re: Transport of a patient with pneumocephalus

[Rollie Parrish <rparrish@flightweb.com>]

On Thu, 18 Dec 2003, Rollie Parrish wrote:

> So, what do you think? If you have a patient with a known
> pneumocephalus, how should they be transported? If it depends on various
> factors, such as volume, concomittant injuries, vital signs, level of
> consciousness, please explain. If your program happens to be able to choose
> between pressurized and non-pressurized aircraft, would this diagnosis
> help influence the mode of transport? Or is this not a
> clinically significant issue for the most part?

I'll go ahead an answer my own question, just to set an example and get
the ball rolling...

I feel that, in general, a patient with this diagnosis should be
transported by pressurized aircraft whenever possible. Even if the
pneumocephalus was determined to be "small" on CT prior to transport
request, there's no guarantee that it hasn't increased with time.
Depending on the situation, the patient may not be able to tolerate
small increases in intracranial pressure. If
there was a deterioration of the patient during transport, I'd hate to
be the one defending a decision to transport unpressurized if
pressurized had been an option.

I've included the abstract of some research into this topic from Sweden
for those interested.

++
Air Transport of Patients with Intracranial Air: Computer Model of
Pressure Effects
Nina Andersson, Helena Grip, Peter Lindvall, Lars-Owe D. Koskinen, Helge
Brändström, Jan Malm, and Anders Eklund
Aviat Space Environ Med 2003; 74:138-44

Introduction: Air is commonly trapped within the skull in patients who
have been treated for trauma or intracranial hemorrhage. In Sweden, when
such a patient is transported by air ambulance it is standard procedure
to maintain sea-level pressure in the cabin to prevent increased
intracranial pressure (ICP). However, this type of flight operation is
more difficult and expensive. Maintenance of sea-level cabin pressure is
not common practice all over the world, and the criteria supporting the
choice of pressurization during transport are inadequate and in need of
evaluation. The purpose of this study was to develop and evaluate a
model to simulate the influence of intracranial air on ICP during air
transport.
Methods: We identified an existing nonlinear model of the
cerebral spinal fluid and intracranial pressure dynamics, then added
intracranial air as a new component and evaluated the model through
simulations.
Results: The model behaved as expected, and the simulations
indicated that under normal flying conditions with decreased cabin
pressure the initial intracranial air volume will increase by
approximately 30% at normal maximum cabin altitude, 8000 ft. The
increase in ICP depends upon both the initial air volume and the rate of
change in cabin altitude. For an intracranial air volume of 30 ml the
estimated worst-case increments of ICP from sea level to maximum
altitude would be from 10 mm Hg to 21.0 mm Hg, or from 20 mm Hg to 31.8
mm Hg.
Discussion: Our results support the need for maintenance of
sea-level pressure during air transport of patients with suspected
intracranial air, since an ICP increment could potentially impair the
patient's clinical condition.

Source:
http://www.asma.org/Publication/abstract/v74n2/v74n2p138.html

++

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Rollie Parrish
FlightWeb: For Air Medical Professionals
http://www.flightweb.com

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